The therapeutic use of certain pyrido[1,2-a]pyrimidine derivatives as antibacterial agents has been described in PCT patent applications WO 9116894, published Nov. 14, 1991, and WO 9510519, published Apr. 20, 1995. Quinolone antibacterial agents are well known and are described, for example, in U.S. Pat. Nos. 4,990,517; 5,140,033; 5,059,597; and PCT application WO 9415938. The U.S. Pat. No. 5,286,723 describes amine substituted spiro compounds which are attached to quinoline derivatives for providing compounds having antibacterial use.
Chiral preparation of 3-aminopyrrolidine derivatives via an optically active tartrate ester intermediate is described in U.S. Pat. No. 5,703,244. Enantioselective synthesis of 3-aminopyrrolidine derivatives by chirally reducing a .beta.-hydroxy ester intermediate is not disclosed.
More efficient processes for the preparation of key chiral intermediates for use in the synthesis of antibiotic agents are needed to ensure the ready availability of the compounds. A process of the invention has not previously been described in the prior art.